判断某年某月多少天的函数

int a[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
int b[13]={0,31,29,31,30,31,30,31,31,30,31,30,31};
int days(int year,int month)
{
	if(year%400==0||year%4==0&&year%100!=0)
	return b[month];
	else
	return a[month];
}